What happens when a valve cover gasket stops working? Not to mention, what is a valve cover gasket?

Let’s backtrack. On a good day, an engine’s pistons move up and down at hyperspeed in the cylinder.

Exhaust valves and gaskets open and close just as fast. They ensure that a constant supply of hot oil keeps an engine’s moving parts lubricated and working at peak capacity.

But nothing’s worse than being stuck on the road with leaking oil and not knowing the cause of it. If you’re wondering what a valve cover gasket is and how it relates to keeping your engine in peak condition (and free of oil leaks), you’ve come to the right place.

We’re Certified Fleet Services, a Florida-based diesel truck repair shop whose mission is to get you back on the road faster. Join us!

In this article, we’ll discuss:

• What a valve cover gasket is
• What it takes to replace a valve cover gasket
• Cost considerations to keep in mind
• Tips to help ensure the health and strength of your diesel vehicles

The importance of a valve cover gasket

Valve cover gaskets play a huge role in your diesel’s health and longevity. A valve cover gasket helps prevent oil from escaping from the engine.

By ensuring a tight seal between the engine and valve cover, the valve cover gasket prevents debris and other harmful particles from entering the space between pistons and engine cylinders.

What happens when a valve cover gasket is worn out or comes loose? More friction, escaped oil, and engine wear and tear occur.

As oil escapes, engine components receive less lubrication and may begin to grind against each other.

The result? More stress on the engine. And more stress increases your chance of needing engine repairs or, worse yet, an engine overhaul.

Knowing the signs of a broken or leaking valve cover gasket will help you make a more informed decision on whether to repair or overhaul your engine or repair its components.

Tell-tale signs of a leaking valve cover gasket

The following tell-tale signs indicate a leaking valve cover gasket:

• Check Engine light goes on: if the check engine light turns on, it may have done so because your engine is low on oil. Low oil can lead to more friction and higher engine temperatures. When an engine experiences higher temperatures and increased friction, engine failure and/or fires can occur. If you notice your check engine light is on, be on the lookout for engine problems, and bring your vehicle to a certified diesel repair technician.
• Engine misfires and rough rides: Often, when a valve cover gasket needs repair work (or replacement), you’ll notice rough riding and engine misfires. The engine may not run smoothly because of misfire issues. Other performance issues can also occur in and around spark plugs. With a faulty valve cover gasket, the chances of engine oil igniting also increase, which means you could have a “fire in the hole,” as the saying goes.
• Unusual oil smell: Sometimes, an oil leak can reach hot engine components, causing a burning oil smell inside the vehicle. Also, the exhaust pipe may emit more exhaust with a broken valve cover gasket.
• Grimy valve covers: if a valve cover is dirty, oily, or filthy with grime, you may have a faulty or leaking cover gasket on your hands. For example, when oil leaks occur, dirt and debris can accumulate inside the vehicle and harden on the valve cover or cylinder head. You’ll want to check your valve cover gasket during each oil change, preventive maintenance, or corrective maintenance repair job to ensure it’s working as it should.

What to expect when replacing faulty valve cover gaskets

Let’s say that you discover one of the tell-tale symptoms of a faulty gasket. Here’s what to expect when replacing an old gasket with a new one — or if fixing a faulty valve gasket.

• Give the engine time to cool: engines run hot. Before diving into its guts and accessing the valve cover, you’ll want to check that your engine is cool. Since you may need to remove other parts like PVC hoses, throttle cables, brackets, and spark plug tubes to access the valve cover, always make sure your engine is cool before conducting repair work.
• Tighten the valve cover: Once your engine is cool — and if your vehicle leaks oil — tighten the valve cover with a torque wrench to stop the leak. If your gasket is worn out, bolt-tightening won’t fix the leak. If you still notice leaks after tightening the gasket, you’ll want to replace the gasket.
• Remove the valve cover: If you need to replace the gasket, remove all valve cover bolts and the valve cover. To ensure nothing falls into the engine, cover the engine while conducting repair work.
• Remove and replace the gasket: grab the old gasket using your hands or a plastic repair tool. You’ll want to avoid using metal repair tools, as the gasket can be prone to grooves and nicks, which can lead to leaks. If needed, you can use a rubber mallet to knock loose and better help you remove the old gasket.
• Add silicone or sealant if needed: We say “if needed” because every engine is different. If your service manual indicates that silicone or sealant is recommended, apply the silicone as needed. Of course, always make sure that surfaces are cleaned before applying the silicone or sealant. Finally, before starting the engine, allow the silicone and/or sealant to cure to ensure a successful repair.

Valve cover gasket replacement costs

One of the most common questions that we’re asked regarding valve cover gaskets is, “How much do they cost?” Valve cover gaskets cost anywhere from $10 to $40.

But, the total cost of repairs can range anywhere between $100 and $230. Therefore, the total cost of a valve gasket replacement can range from $110 to $340 depending on the scope of the repair.

This number includes replacing the valve cover gasket and installing a new gasket along with other key components. For the most up-to-date estimate in your area, we recommend contacting your local diesel truck repair shop.

Table: Valve cover gasket replacements, costs, and more

1 Million miles: Did you know?

1 million miles: imagine seeing that number on your dashboard. Did you know that a semi-truck’s engine can go for 1 million miles before it needs replacing?

And with more than 13 billion miles logged by semi-truck drivers in 2016 (and that’s just in the state of Texas), there’s a strong probability that trucks will become more efficient in the future.

 With proper preventive maintenance and fleet care, your semi-truck can drive long and strong, day and night!

Pro tip: Trust certified mechanics for valve cover gasket repairs

Depending on the model of the vehicle, replacing a valve cover gasket can be a sinch. But without professional help, drivers risk debris and small particles falling inside the engine space when performing do-it-yourself repairs.

What’s more, a worn-out gasket can spell trouble, allowing oil to leak into other parts of the engine, which can cause performance issues.

And if the engine and the valve cover aren’t replaced correctly the first time, drivers might shell out more money than needed.

Pro tip: get your repair work done right the first time. A little upfront investment can save you a ton of money, stress, and hassle in the long run.

If your gasket needs to be replaced, hop on over to any of our three Florida-based locations. Whether you need a new seal — or an ear for how to resolve valve cover leaks on your own — our ASE-certified diesel technicians would be happy to help.

Contact us today for all your fleet and diesel truck repair needs.

Frequently asked questions (FAQ) about valve cover gaskets

What exactly is a valve cover gasket?

A valve cover gasket is a seal between an engine and its valve cover. The seal is made of rubber, plastic, or cork.

The gasket’s job is to help prevent the oil circulating through the engine from escaping from the engine. A worn out or broken gasket can cause leaks — and debris and small particles to enter the space between engine pistons and cylinders.

Leaks and debris can cause damage to a vehicle.

How do I replace a valve cover gasket?

If you’re thinking of replacing a valve cover, we always recommend doing so with a certified diesel mechanic first. But, if you’re intent on doing the repair work yourself, follow these five gasket instructions:

• Give the engine time to cool before replacing parts
• Tighten the valve cover (to ensure the issue isn’t related to a leak)
• Replace the valve cover
• Remove and replace the gasket (if the gasket materials are worn out)
• Add silicone if needed

Can I replace a valve cover gasket by myself?

Definitely. You can always buy the tools and supplies needed to conduct a valve cover replacement if you have the time and resources to do so.

We always recommend enlisting the help of an ASE-certified diesel mechanic, as diesel repair technicians spend hours daily working on diesel repair equipment. Plus, they have the knowledge and experience to ensure your repair job goes off without a hitch the first time around.